Catalytic enantioselective Mannich reactions provide one of the most versatile and attractive approaches for the generation of optically active chiral amines. Reviews: (a) Marques, M. M. B. Angew. Chem., Int. Ed. 2006, 45, 348. (b) Shibasaki, M.; Matsunaga, S. J. Organomet. Chem. 2006, 691, 2089. (c) Cordova, A. Acc. Chem. Res. 2004, 37, 102. (d) Kobayashi, S.; Ueno, M. In Comprehensive Asymmetric Catalysis Supplement I; Jacobsen, E. N., Pfaltz, A., Yamamoto, H., Eds.; Springer: Berlin, 2003 Chapter 29.5.
While great strides have been made over the last several years with both chiral metal and organic catalysts, only a few catalytic asymmetric Mannich reactions include both carbamate-protected aryl and alkyl imines as substrates. For recent reports of catalytic asymmetric Mannich reactions catalyzed by chiral metal-complexes, see (a) Sasamoto, N.; Dubs, C.; Hamashima, Y.; Sodeoka, M. J. Am. Chem. Soc. 2006, 128, 14010. (b) Trost, B. M.; Jaratjaroonphong, J.; Reutrakul, V. J. Am. Chem. Soc. 2006, 128, 2778. (c) Ihori, Y.; Yamashita, Y.; Ishitani, H.; Kobayashi, S. J. Am. Chem. Soc. 2005, 127, 15528. (d) Harada, S.; Handa, S.; Matsunaga, S.; Shibasaki, M. Angew. Chem. Int. Ed. 2005, 44, 4365. (e) Hamashima, Y.; Sasamoto, N.; Hotta, D.; Somei, H.; Umebayashi, N.; Sodeoka, M. Angew. Chem. Int. Ed. 2005, 44, 1525. (f) Kobayashi, S.; Ueno, M.; Saito, S.; Mizuki, Y.; Ishitani, H.; Yamashita, Y. Proc. Natl. Acad. Sci. USA 2004, 101, 5476. (g) Akiyama, T.; Itoh, J.; Yokota, K.; Fuchibe, K. Angew. Chem. Int. Ed. 2004, 43, 1566. (h) Josephsohn, N. S.; Snapper, M. L.; Hoveyda, A. H. J. Am. Chem. Soc. 2004, 126, 3734. (i) Marigo, M.; Kjærsgaard, A.; Juhl, K.; Gathergood, N.; Jørgensen, K. A. Chem. Eur. J. 2003, 9, 2359. (j) Natsunnga, S.; Kumagai, N.; Harada, S.; Shibasaki, M. J. Am. Chem. Soc. 2003, 125, 4712. (k) Kobayashi, S.; Matsubara, R.; Nakamura, Y.; Kitagawa, H.; Sugiura, M. J. Am. Chem. Soc. 2003, 125, 2507. (l) Bernardi, L; Gothelf, a. Hazell, R. Jørgensen, K. A. J. Org. Chem., 2003, 68, 2583 (m) Trost, B. Terrell, L. R. J. Am. Chem. Soc. 2003, 125, 338. (n) Kobayashi, S.; Hamada, T.; Manabe, K. J. Am. Chem. Soc. 2002, 124, 5640. For recent reports of asymmetric Mannich reactions catalyzed by chiral organic catalysts, see (a) Zhang, H. L.; Mifsud, M.; Tanaka, F.; Barbas, III, C. F. J. Am. Chem. Soc. 2006, 128, 9630. (b) Song, J.; Wang, Y.; Deng, L. J. Am. Chem. Soc. 2006, 128, 6048. (c) Tillman, A. L.; Ye, J.; Dixon, D. J. Chem. Commun. 2006, 1191. (d) Ting, A.; Lou, S.; Schaus S. E. Org. Let. 2006, 8, 2003. (e) Mitsumori, S.; Zhang H.; Cheong, P. H.; Houk, K. N.; Tanaka, F.; Barbas, C. F., III. J. Am. Chem. Soc. 2006, 128, 1040. (f) Kano, T.; Yamaguchi, Y.; Tokuda, O.; Maruoka, K. J. Am. Chem. Soc. 2005, 127, 16408. (g) Lou, S.; Taoka, B. M.; Ting, A.; Schaus, S. E. J. Am. Chem. Soc. 2005, 127, 11256. (h) Poulsen T. B.; Alemparte, C.; Saaby, S.; Bella, M.; Jorgensen, K. A. Angew. Chem. Int. Ed. 2005, 44, 2896 (i) Uraguchi, D.; Terada, M. J. Am. Chem. Soc. 2004, 126, 5356. (j) Notz, W.; Tanaka, F.; Barbas III, C. F. Acc. Chem. Res. 2004, 37, 5801. (k) Zhuang, W.; Saaby, S.; Jørgensen, K. A. Angew. Chem. Int. Ed. 2004, 43, 4476 (l) Córdova, A. Chem. Eur. J. 2004, 10, 1987. (m) Notz, W.; Watanabe, S.-I.; Chowdari, N. S.; Zhong, G.; Betancort, J. M.; Tanaka, F.; Barbas, III, C. F. Adv. Synth. Catal. 2004, 346, 1131. (n) Hayashi, Y.; Tsuboi, W.; Ashimine, I.; Urushima, T.; Shoji, M.; Sakai, K. Angew. Chem. Int. Ed. 2003, 42, 3677. (o) Wenzel, A. G.; Lalonde, M. P.; Jacobsen, E. N. Synlett 2003, 1919. (p) Wenzel, A. G.; Jacobsen, E. N. J. Am. Chem. Soc. 2002, 124, 12964. (q) List B.; Pojarliev, P.; Biller, W. T.; Martin, H. J. J. Am. Chem. Soc. 2002, 124, 827. (r) List, B. J. Am. Chem. Soc. 2000, 122, 9336. For an asymmetric Mannich reaction catalyzed by a phase transfer catalyst, Okada, A.; Shibuguchi, T.; Ohshima, T.; Masu, H.; Yamaguchi, K.; Shibasaki, M. Angew Chem., Int. Ed. 2005, 44, 4564.
Palomo and the group of Herrera, Bernardi and Ricci independently reported highly enantioselective aza-Henry reactions with in situ generation of carbamate-protected aryl and alkyl imines from α-amido sulfones 1A promoted with a chiral phase transfer catalyst, thereby establishing asymmetric Mannich reactions tranforming directly the stable α-amido sulfones 1 into the corresponding aza-Henry (Mannich) adducts. Palomo, C.; Oiarbide, M.; Laso, A.; Lopez, R. J. Am. Chem. Soc. 2005, 127, 17622; and Fini, F.; Sgarzani, V.; Pettersen, D.; Herrera, R. P.; Bernardi, L.; Ricci, A. Angew. Chem., Int. Ed. 2005, 44, 7975. For a comprehensive review of using α-amido sulfones as stable precursors of N-acylimino derivatives, see Petrini, M. Chem. Rev. 2005, 105, 3949.